Shroomboom
Type: Life
How to get: Dragonfire Cannon 3-Pack (w/ Chop Chop and Dragonfire Cannon), Golden Dragonfire Cannon 3-Pack (w/ Chop Chop and Dragonfire Cannon - GameStop Exclusive)
Variations: 

Proving that the Skylanders world is weird, Shroomboom is a mushroom that was previously groomed to be a pizza topping. He bucked the trend, though, and made a slingshot that helped him escape and go fight against Kaos.

• Starting Abilities: Unknown
• Initial Upgrades: Unknown
• Path 1: Unknown
• Path 2: Unknown
• Soul Gem Ability: Unknown
• 3DS Abilities: Unknown

Tree Rex
Type: Life Giant
How to get: Skylanders Giants Starter Pack, Skylanders Giants Booster Pack, PlayStation 3 Bundle (Gnarly)
Variations: Gnarly Tree Rex

Tree Rex is a giant tree who has every type of move you would want in a Skylanders: a close-up melee attack, an offensive dash move, and a projectile. Basically, he's the best giant to be included as a starter. Also, he warns you to not be afraid of the bark, which is hysterical.

• Starting Abilities
• Shockwave Slam (A button; slam ground causing shockwaves)
• Sequoia Stampede (B button; dash attack)
  
  
• Initial Upgrades
• Photosynthesis Cannon (Z button; shoot light beams)
• Big Thorn Shockwave Slam (Hold A button for better Shockwave Slam)
• Super Stampede (Sequoia Stampede does more damage)
• Treefolk Tripleshot (Photosynthesis Cannon fires triple shots)
  
  
• Path 1
• Titanic Elbow Drop (Press A button while using Sequoia Stampede to do an elbow drop)
• Lightfooted (Sequoia Stampede lasts longer)
• Ultimate Stampede (Sequoia Stampede does more damage)
  
  
• Path 2
  
• Super-Charged Vaporizer (Hold Z button to charge Photosynthesis Cannon)
• Sun Skewer (Photosynthesis Cannon blasts through enemies)
• The Pod Maker (Vaporized enemies turn into exploding plant pods)
  
  
• Soul Gem Ability: Woodpecker Pal (summon woodpecker; found in Molekin Mountain)